Like you, the St. Lawrence River changes…especially in terms of its geography. Find some phenomena that occur quickly (short term) and some that occur over a longer period of time (long term).

Short-term changes

Long-term changes

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Short-term changes

Flooding

Heavy rains can cause lakes and rivers to flood very quickly. In the Saguenay region, in July 1996, six rivers flooded over only three days, breaking dams and changing the landscape considerably.

Photo: Musée du Fjord

Low tide, high tide

Tides are controlled mainly by the pull of the Moon and Sun on bodies of water. Every day, there are two high tides and two low tides whose range various from day to day and also by location.

Photo: Musée du Fjord

Ice jams

In the spring, the ice covering rivers and streams breaks into pieces that drift off. This is called break-up. Sometimes, the ice gets stuck and prevents the water from flowing. We refer to this as an ice jam.

Photo: F. Méaulle, colorié par http ://www.antique-prints.de/

Long-term changes

Fossils

Fossils result from the changes a living organism undergoes after dying and being buried in the ground. Fossilization is a long, slow process that can take thousands of years.

Photo: Caroline Julien

Formation of a fjord

The creation of a fjord like the Saguenay Fjord takes hundreds of millions of years. This valley was sculpted by ice flowing over it. The area then filled with seawater.

Photo: Caroline Julien

Glacial erratic

Sometimes, boulders are caught in a glacier and carried for many kilometers over hundreds of years. They are left when the glacier melts. This explains why we find them in unusual places, like the middle of a forest!